Results From Phase III of the Sudbury Neutrino ObservatoryResults From Phase III of the Sudbury...
Transcript of Results From Phase III of the Sudbury Neutrino ObservatoryResults From Phase III of the Sudbury...
Results From Phase III of the Sudbury Neutrino Observatory
Jason GoonLouisiana State University
forThe Sudbury Neutrino Observatory
CollaborationCosmo 2008, Madison WI, Aug 2008
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Outline� Physics and Reactions � Motivation� Detectors and Detections� Signal Extraction and Analysis� Summary1998 1999 2000 2001 2002 2003 2004 2005 2006
Comm.
D2O
Salt
D2O
D2OReturn
DataAnalysis
3He
SNO
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Solar reactions and spectra
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3 Reactions:
1700 tonnes InnerShield H2O
1000 tonnes D2O
5300 tonnes Outer Shield H2O
12 m Diameter Acrylic Vessel
Support Structure for 9500 PMTs, 60% coverage
6000 mwe overburden
ν x + e− → ν x + e−
ν e + d → p + p + e−
νx + d → p + n + νx
3 neutron detection methods:n + d → t + γ + 6.25
n+35Cl→36Cl + γ + 8.6
n+3He → p + t + 0.76
3 Phases: • Just D2O• D2O + 2 tonnes NaCl• D2O + 3He Proportional Counters (“NCDs”)
SNOESCC
NC
MeV
MeV
MeV
Image courtesy National Geographic
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Motivation
� Separate CC and NC signal paths: neutron capture no longer competes with CC events in Cherenkov light.(CC spectrum contamination by 6.25-MeV capture gammas reduced by capture in NCD array, and determined independently)
� Break correlation between CC and NC signals� Signal extraction of CC, ES, NC analysis employs
“Floating systematics”
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A PMT neutrino
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Eve
nts
per
10 k
eV
Neutrons from 24Na: γ + d→p + n
191
keV
573
keV
764
keV
191573
p
tn
Ni wall3He:CF4 gas
Cu anode wire
573
191
NCD Counters 2 - 3m long laser-welded together and deployed by a submersible vehicle.36 strings of 3He, 4 strings of 4He on a 1 x 1 m grid.
Neutron spectrum is obtained from 24Na calibration source
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Sigex Extraction�Joint-fits: 2 data streams (PMT and NCD)�PMT-NC signal constrained to NCD-NC signal�Performed at PMT e- kinetic thres. > 6 MeV.�Energy spectral shape is unconstrained.�3 different and independent sigex codes�All 3 sigex codes used likelihood functions
The physics parameters (“fluxes”) are fitted allowing nuisance parameters (calibration constants, etc.) to vary weighted by their external uncertainties. The likelihood is maximized via randomized search steps
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Blind and Box AnalysisBlind
� First month of open dataset (26.7days) and 359.5 days of blind dataset which consist of hidden fraction of neutrons that follow muons, AND Omit an unknown fraction of candidate events
� Analyze with 3 different sigex codes and blind comparison
Box open on 2nd of May 2008
� Results presented are as found, except…
� Difference between uncertainties from 3 signal-extraction codes: “Pilot errors” corrected, no change in central values, uncertainties agree.
� An incorrect algorithm in fitting the peak of the ES posterior distributions replaced
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Backgrounds
185 +25-2277 +12
-10TOTAL
40.9 ± 20.620.6 ± 10.4External-source neutrons
8.0 ± 5.21.1 ± 1.0NCD cables
64.4 ± 6.417.7 ± 1.8NCD hotspots
27.6 +12.9-10.34.6 +2.1
-1.6NCD Bulk PD, 17,18O(α,n)
2.3 ± 0.30.7 ± 0.1Other backgrounds
13.6 ± 2.724.7 ± 4.6Atmospheric ν, 16N
28.7 ± 4.77.6 ± 1.2D2O Radioactivity
NCD Events (neutrons)
PMT Events (neutrons)
Source
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NCD neutrons from solar neutrino interactions
NC Signal:983 ± 77
Neutron background:185 ± 25
Alphas and Instrumentals:6126 ± 250(0.4 to 1.4 MeV)
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PMT Distributions - cos(θsun), Energy
Data from salt phase
PMT Kinetic Energy (MeV)
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SNO NC Flux: 3 Phases
CC spectrum shape not constrained to 8B shape.NC Flux (corrected to 8B spectrum of Winter et al.)
stat stat + syst
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SNO CC and ES Fluxes: 3 Phases
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Results from SNO NCD Phase & Super-K
φSSM = 5.69(1±0.16) x 106 cm-2 s-1 (BSB05-OP: Bahcall, Serenelli, Basu Ap. J. 621, L85, 2005).Super-K: PRD 73, 112001, 2006
Fluxes
(106 cm-2 s-1)
νe: 1.67(9)
νES: 1.77(26)
νtotal: 5.54(48)
νSSM: 5.69(91)
φCC = νe
φES = νe + 0.154νµτφNC = νe + νµτ
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2-Neutrino Oscillation Contours
SNO only
Solar Solar + KamLAND
Cl-ArSuper-KSAGEGallexGNOSNOBorexino
766 t-y KamLAND
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Summary� Good agreement between NCD and previous
SNO phase results and with theory� Minimal NC and CC correlation
� New precision on θ
∆m2 = 7.94−0.26+0.42 ×10−5 eV2
degrees
tan2θ =0.447−0.043+0.047
θ = 33.8−1.3+1.4 φ8B =0.873(1± x)φ8B(BSB05−OP)
Solar + KamLAND fit results
2-neutrino mixing model. Marginalized 1-σ uncertainties. All SNO phases.KamLAND: PRL 94, 081801 (2005). x to be published later.
Sin2θ12 ~ ΦCC/ΦNC = 0.301+0.033 (tot)
J. TM. Goon, T. Kutter, K. McBrydeLouisiana State University
J.A. Formaggio, M.L. Miller, B. Monreal, J. Monroe,R.A. Ott, T.J. Walker
MIT
S.D. Biller, B.T. Cleveland, G. Doucas, H. Fergani, N.A. Jelley, J.C. Loach, S. Majerus,
H.M. O’Keeffe, G.D. Orebi Gann, P.M. Thornewell, H. Wan Chan Tseung, N. West, J.R. Wilson, K. Zuber
Oxford University
E.W. Beier, H. Deng, M. Dunford, W.J. Heintzelman, C.C.M. Kyba, N. McCauley, J.A. Secrest, R. Van Berg
University of Pennsylvania
S.N. Ahmed, B. Cai, M. Chen, X. Dai, M. DiMarco, E.D. Earle,H.C. Evans, G.T. Ewan, E. Guillian, P.J. Harvey, J. Heise, K.J. Keeter, L.L. Kormos, M.S. Kos, C. Kraus, J.R. Leslie,
R. MacLellan, H.B. Mak, R. Martin, A.B. McDonald, A.J. Noble,B.C. Robertson, P. Skensved, A. Wright, Y.Takeuchi
Queen’s University
F. Duncan, R. Ford, I.T. Lawson, B. MorissetteSNOLAB
R.L. HelmerTRIUMF
A.E. Anthony, J.R. Klein, S. Seibert, C.D. TunnellUniversity of Texas at Austin
J.F. Amsbaugh, M.C. Browne, T.V. Bullard, T.H. Burritt, G.A. Cox-Mobrand, J. Detwiler, P.J. Doe, C.A. Duba, N. Gagnon, J.V. Germani, A. Hamian, G.C. Harper, R. Hazama, K.M. Heeger, M.A. Howe, S. McGee, A. Myers, N.S. Oblath, R.G.H. Robertson,
M.W.E. Smith, T.D. Steiger, B.A. VanDevender, T. Van Wechel, B.L. Wall, J.F. Wilkerson
University of Washington
The SNO Collaboration
B. Beltran, S. Habib, A.L. Hallin, C. Howard, C.B. KraussUniversity of Alberta
B. Jamieson, S.M. Oser, T. Tsui, J. WendlandUniversity of British Columbia
R.L. Hahn, R. Lange, M. YehBrookhaven National Laboratory
A.Bellerive, K. Boudjemline, P.-L. Drouin, K. Graham, R.J. Hemingway, C. Mifflin, E. Rollin, O. Simard, L. Sinclair,
G. Tesic, D. Waller, F. ZhangCarleton University
P. Jagam, J. Law, B.G. Nickel,R.W. Ollerhead, S.D. Reitzner, J.J. Simpson
University of Guelph
B. Aharmim, D. Chauhan, J. Farine, F. Fleurot, E.D. Hallman,M. Huang, A. Krueger, M.H. Schwendener, C.J. Virtue
Laurentian University
M. Bergevin, Y.D. Chan, C.A. Currat, R. Henning, K.T. Lesko,A.W.P. Poon, G. Prior, N. Tolich
Lawrence Berkeley National Laboratory
N. Barros, J. ManeiraLIP, Lisbon
J. Banar, T.J. Bowles, S.R. Elliott, M.M. Fowler, A. Goldschmidt, A. Hime, G.G. Miller, K. Rielage,
L.C. Stonehill, J.B. Wilhelmy, J.M. WoutersLos Alamos National Laboratory